Windowed Unit Tests

[richardeakin]

We introduced unit tests in 0.9.1, which are run on the command line with a headless application. We need a Window to test some things, particularly in OpenGL or something else that requires a window context, which we don't yet have.

We probably want to still have an option to run unit tests without a Window, for situations where we're deploying to something that can't make a window. So we should probably create a second unit project that sets up a windows application, like we would normally construct a cinder application. We should also keep in mind how we'll run this with remote CI.